Unequivocal Observation Research Articles

Pathological Basis of Imaging in Hepatocellular Carcinoma

AbstractHepatocellular carcinoma (HCC) is the most prevalent form of liver cancer with major risk factors being chronic liver disease (CLD) including chronic liver inflammation, steatohepatitis and certain viral infections (Hepatitis B and C). Due to the poor prognosis, early detection is key for effective management. Imaging of HCC has developed over the years with specificity as high as 95%. The Liver Imaging Reporting and Data System (LI-RADS) provides a standardized reporting format that can be followed by radiologists and clinicians alike. This article focuses on the pathological basis of imaging observations described in the LI-RADS lexicon. A clear understanding of the pathological basis of imaging will help the radiologist to be more confident to resolve unequivocal observations apart from achieving a high degree of specificity in the diagnosis of HCC.

Atomically Resolved Quantum-Confined Electronic Structures at Organic-Inorganic Interfaces of Two-Dimensional Ruddlesden-Popper Halide Perovskites.

This work demonstrates the direct visualization of atomically resolved quantum-confined electronic structures at organic-inorganic heterointerfaces of two-dimensional (2D) organic-inorganic hybrid Ruddlesden-Popper perovskites (RPPs); this is accomplished with scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) by using solvent engineering to prepare perpendicularly oriented 2D RPPs. Atomically resolved band mapping images across the organic-inorganic interfaces of 2D RPPs yield typical quantum-well-like type-I heterojunction band alignment with band gaps depending on the thicknesses or n values of the inorganic perovskite slabs. The presence of edge states within the band gap due to organic cation vacancies is also observed. In addition, real-space visualization of atomic-scale structural phase transition behavior and changes in local electronic band structures are obtained simultaneously. Our results provide an unequivocal observation and explanation of the quantum-confined electronic structures formed at organic-inorganic interfaces of 2D RPPs.

Constraining the Lensing of Binary Black Holes from Their Stochastic Background.

Gravitational waves (GWs) are subject to gravitational lensing in the same way as electromagnetic radiation. However, to date, no unequivocal observation of a lensed GW transient has been reported. Independently, GW observatories continue to search for the stochastic GW signal that is produced by many transient events at high redshift. We exploit a surprising connection between the lensing of individual transients and limits to the background radiation produced by the unresolved population of binary back hole mergers: we show that it constrains the fraction of individually resolvable lensed binary black holes to less than ∼4×10^{-5} at present sensitivity. We clarify the interpretation of existing, low redshift GW observations (obtained assuming no lensing) in terms of their apparent lensed redshifts and masses and explore constraints from GW observatories at future sensitivity. Based on our results, recent claims of observations of lensed events are statistically disfavored.

Can digital consumption boost physical consumption? The effect of online music streaming on record sales

Despite a consensus that sales of physical albums have declined with the increasing prevalence of digital music, this seemingly unequivocal observation may not be true. Physical formats still occupy a fraction of the market, with a noticeable increase in the sales of physical albums in a few countries where digital media is predominant. This study empirically examines the impact of two online music channels (streaming and downloading) on physical album sales in the South Korean music market. By utilizing a unique dataset representing nationwide music sales, our empirical findings suggest that the growth in digital music services can be positively associated with an increase in physical album sales. In particular, this finding is more salient for male, solo, and lesser-known artistes. This empirical evidence implies that burgeoning music streaming services (access-based digital consumption) may lead to another ownership-based physical consumption. Our findings provide useful managerial implications for practitioners in countries where streaming services are growing.

Radical or Not Radical: Revisiting Lithium–Sulfur Electrochemistry in Nonaqueous Electrolytes

or S 2 ·− were detected). This was also the only radical species observed by Barchasz et al. [ 12 ] upon discharge of a sulfur electrode in tetraethylene glycol dimethyl ether (TEGDME). None of these studies, however, gives a quantitative estimate of the free radical content in the electrolyte, as compared with the various S n 2− dianions. Is the S 3 ·− radical prominent upon cycling in Li–S cells using dimethoxyethane (DME) and 1,3-dioxolane (DOL) solvents? In this event, could its reactivity be held responsible—through electrolyte decomposition—for capacity fading over extended cycling? If not, could the practical capacity of a Li–S cell be augmented by favoring free radicals by tuning the dielectric characteristics of the electrolyte? Herein, we assess the effect of sulfur radical species formed upon cycling of Li–S cells; in particular S 3 ·− . Based on our unequivocal observation of sulfur radicals in a Li–S cell by X-ray absorption near edge structure (XANES)—for the fi rst time under operating conditions—using an EPD solvent (DMA), we show that radicals are not stabilized in glyme-based electrolytes. However, we do show that S 3 ·− reacts with DOL at elevated temperatures, while DME remains intact. In contrast, the much greater dissociation of the anion precursor, S 6 2− , to the trisulfur radical in donor solvents such as DMA and DMSO—where trisulfur is in high concentration but nonreactive—surprisingly and importantly allows the full utilization of both sulfur and Li 2 S. The effective solvation of the latter results in the complete absence of an overpotential on charge. Chemical incompatibility between the lithium metal negative electrode and EPDsolvents can be overcome with anode protection, demonstrating their applicability as electrolytes for the Li–S or Li 2 S batteries in hybrid cells. The nature of sulfur species in nonaqueous solutions of alkali polysulfi des has been well established since the 1970s, using UV–Visible or electron spin resonance spectroscopies in various solvents. [ 9,10,12 ] It is not the scope of this work to repeat such experiments, and we accept that solvents with low donor number (DN), such as tetrahydrofuran (THF) contain exclusively dianions, and in particular S 4 2− and S 6 2− that give rise to a yellow coloration ( Figure 1 a,e). In contrast, solvents with high DN give intensely colored blue solutions owing to the S 3 ·−

Josephson supercurrent through a topological insulator surface state

Topological insulators are characterized by an insulating bulk with a finite band gap and conducting edge or surface states, where charge carriers are protected against backscattering. These states give rise to the quantum spin Hall effect without an external magnetic field, where electrons with opposite spins have opposite momentum at a given edge. The surface energy spectrum of a threedimensional topological insulator is made up by an odd number of Dirac cones with the spin locked to the momentum. The long-sought yet elusive Majorana fermion is predicted to arise from a combination of a superconductor and a topological insulator. An essential step in the hunt for this emergent particle is the unequivocal observation of supercurrent in a topological phase. Here, we present the first measurement of a Josephson supercurrent through a topological insulator. Direct evidence for Josephson supercurrents in superconductor (Nb) - topological insulator (Bi2Te3) - superconductor e-beam fabricated junctions is provided by the observation of clear Shapiro steps under microwave irradiation, and a Fraunhofer-type dependence of the critical current on magnetic field. The dependence of the critical current on temperature and length shows that the junctions are in the ballistic limit. Shubnikov-de Haas oscillations in magnetic fields up to 30 T reveal a topologically non-trivial two-dimensional surface state. We argue that the ballistic Josephson current is hosted by this surface state despite the fact that the normal state transport is dominated by diffusive bulk conductivity. The lateral Nb-Bi2Te3-Nb junctions hence provide prospects for the realization of devices supporting Majorana fermions.

ChemInform Abstract: An EXAFS Study of the Metallofullerene YC82: Is the Yttrium Inside the Cage?

A sample, determined by time-of-flight mass spectroscopy (TOFMS) to consist of YC 82 as the major metal-fullerene complex, was analyzed by X-ray absorption spectroscopy. The Y is found to have 7±1 near-neighbor C atoms at 2.35±0.02 Aand an Y neighbor at 4.05±0.05 A. The unequivocal observation of an Y-Y interaction is unexpected, since the mass spectral data show no indication of Y 2 C n as a major component of the sample. We believe that the combined TOFMS and extended X-ray absorption fine structure (EXAFS) results are not consistent with models that place the metal ion inside the fullerene cage

Real-time measurement of solute transport within the lacunar-canalicular system of mechanically loaded bone: Direct evidence for load-induced fluid flow

Since proposed by Piekarski and Munro in 1977, load-induced fluid flow through the bone lacunar-canalicular system (LCS) has been accepted as critical for bone metabolism, mechanotransduction, and adaptation. However, direct unequivocal observation and quantification of load-induced fluid and solute convection through the LCS have been lacking due to technical difficulties. Using a novel experimental approach based on fluorescence recovery after photobleaching (FRAP) and synchronized mechanical loading and imaging, we successfully quantified the diffusive and convective transport of a small fluorescent tracer (sodium fluorescein, 376 Da) in the bone LCS of adult male C57BL/6J mice. We demonstrated that cyclic end-compression of the mouse tibia with a moderate loading magnitude (–3 N peak load or 400 µɛ surface strain at 0.5 Hz) and a 4-second rest/imaging window inserted between adjacent load cycles significantly enhanced (+31%) the transport of sodium fluorescein through the LCS compared with diffusion alone. Using an anatomically based three-compartment transport model, the peak canalicular fluid velocity in the loaded bone was predicted (60 µm/s), and the resulting peak shear stress at the osteocyte process membrane was estimated (∼5 Pa). This study convincingly demonstrated the presence of load-induced convection in mechanically loaded bone. The combined experimental and mathematical approach presented herein represents an important advance in quantifying the microfluidic environment experienced by osteocytes in situ and provides a foundation for further studying the mechanisms by which mechanical stimulation modulates osteocytic cellular responses, which will inform basic bone biology, clinical understanding of osteoporosis and bone loss, and the rational engineering of their treatments. © 2011 American Society for Bone and Mineral Research.

First Results from the THEMIS Mission

THEMIS was launched on February 17, 2007 to determine the trigger and large-scale evolution of substorms. During the first seven months of the mission the five satellites coasted near their injection orbit to avoid differential precession in anticipation of orbit placement, which started in September 2007 and led to a commencement of the baseline mission in December 2007. During the coast phase the probes were put into a string-of-pearls configuration at 100 s of km to 2 RE along-track separations, which provided a unique view of the magnetosphere and enabled an unprecedented dataset in anticipation of the first tail season. In this paper we describe the first THEMIS substorm observations, captured during instrument commissioning on March 23, 2007. THEMIS measured the rapid expansion of the plasma sheet at a speed that is commensurate with the simultaneous expansion of the auroras on the ground. These are the first unequivocal observations of the rapid westward expansion process in space and on the ground. Aided by the remote sensing technique at energetic particle boundaries and combined with ancillary measurements and MHD simulations, they allow determination and mapping of space currents. These measurements show the power of the THEMIS instrumentation in the tail and the radiation belts. We also present THEMIS Flux Transfer Events (FTE) observations at the magnetopause, which demonstrate the importance of multi-point observations there and the quality of the THEMIS instrumentation in that region of space.

Ephemeral sand waves in the hurricane surf zone

Airborne bathymetric LIDAR observations along the Florida panhandle after Hurricane Dennis (2005) show the first unequivocal observations of surf-zone sand wave trains. These are found in depths of ∼ 5m along the trough of the hurricane bar, where hindcasts show strong longshore currents only during severe storms. The waves extend over tens of kilometers of coast after Dennis but are absent from the same area in four other datasets. Observed wavelength to water depth ratios are comparable to river dunes and tidal sand waves but height to depth ratios are smaller, with the largest wave heights around 0.1 times the water depth. The sand wave generation mechanism is hypothesized to be from wind-and-wave-induced longshore currents, which were hindcast to be large during Dennis, with destruction from water wave orbital velocities.

Record of grey weevil, Myllocerus discolor (nr.) Boheman (Coleoptera: Curculionidae) grub infesting roots of Teak (Tectona grandis L.F.) seedlings in Maharashtra

An unequivocal observation on the damage caused by the grubs of Grey weevil; Myllocerus discolor (nr.) Boheman, to the roots of Teak seedlings in Maharashtra has been reported. The infested seedlings succumbed to the injury and died. Period and pattern of infestation, incidence level and description of grub, pupa, and adult with their possible control measures have been discussed. This is the first evidence of curculionid, M. discolor grubs infesting on forest tree host.

Conserved Mechanism of Copper Binding and Transfer. A Comparison of the Copper-Resistance Proteins PcoC from Escherichia coli and CopC from Pseudomonas syringae

The copper-resistance proteins PcoC from Escherichia coli and CopC from Pseudomonas syringae exhibit 67% sequence identity, but the chemistry reported for PcoC (Peariso, K.; Huffman, D. L.; Penner-Hahn, J. E.; O'Halloran, T. V. J. Am. Chem. Soc. 2003, 125, 342-343) was distinctly different from that reported for CopC (Zhang, L.; Koay, M.; Maher, M. J.; Xiao, Z.; Wedd, A. G. J. Am. Chem. Soc. 2006, 128, 5834-5850). The source of the inconsistency has been identified, and His1 is confirmed as an unprecedented bidentate ligand in each protein. Access to a bona fide wild-type PcoC protein allowed unequivocal observation of intermediates involved in intermolecular redox copper transfer reactions.

Typical applications of MARY spectroscopy: Radical ions of substituted benzenes

The paper describes the underlying principles and discusses the most important advantages and limitations of the experimental technique of magnetically affected reaction yield spectroscopy as developed in the authors’ laboratory and guides the reader step by step through a typical experimental sequence using as example the problem of short-lived radical cations of a series of methyl-substituted benzenes in X-irradiated nonpolar solutions. For two of the eight target substances — benzene itself and mesithylene — the paper reports the first unequivocal observation of their radical cations in liquid alkane solution at room temperature and provides a lower estimate of about 10 ns for their relaxation times in low magnetic field.

Ultrafast Charge Separation from the S2Excited State of Directly Linked Porphyrin−Imide Dyads: First Unequivocal Observation of the Whole Bell-Shaped Energy-Gap Law and Its Solvent Dependencies

Photoinduced charge separation (CS) due to electron transfer from the S2 state of zinc porphyrin (ZP) to a directly linked imide (I) has been studied by means of femtosecond fluorescence up-conversion and femtosecond−picosecond transient absorption spectral measurements. S2 fluorescence decay curves of ZP−I dyads in various solvents were all single-exponential, from which accurate rate constants for the CS reaction were obtained. The whole bell-shaped energy-gap law (EGL) has been confirmed unambiguously in polar solvents tetrahydrofurane, acetonitrile, and triacetin as the first example for CS, which can be reproduced on the basis of a nonadiabatic mechanism considering solvent reorganization and intrachromophore high-frequency vibrations (hfm) approximated by an averaged single mode. Mainly the top and inverted regions have been observed in nonpolar solvents cyclohexane and toluene. This result may be ascribed to the large decrease of the solvent reorganization energy in nonpolar solvents, which causes a large shift in the reaction coordinate for CS, making the S2-state surface partially embedded in that of the CS state and transforming the EGL for the CS reaction into one that is somewhat analogous to that of the radiationless transition in the weak-coupling limit. The single-exponential fluorescence decay in 100 fs and the EGL with both normal and inverted regions observed in triacetin indicate strongly that very fast solvent relaxation should take place despite the very long τL of 125 ps at 20 °C (see the text). Thus, by using specifically designed ZP−I linked systems, we have directly demonstrated that both the intramolecular hfm and ultrafast solvent relaxation play very important roles in the ultrafast CS from the S2 state and that we can regulate its EGL by controlling the nature of the solvent.

Image-potential-induced states at metal surfaces

The unequivocal observation in the early 1980s of a new class of unoccupied surface states that are bound to the vacuum level of a variety of metal surfaces has led over the last two decades to an active area of research in condensed-matter and surface physics. We discuss the key ingredients of the theory of these so-called image states, which have their origin in the long range nature of the image potential outside a solid.

First unequivocal observation of the whole bell-shaped energy gap law in intramolecular charge separation from S(2) excited state of directly linked porphyrin-imide dyads and its solvent-polarity dependencies.

First unequivocal observation of the whole bell-shaped energy gap law in intramolecular charge separation from S(2) excited state of directly linked porphyrin-imide dyads and its solvent-polarity dependencies.

The observation of inner core shear waves

Summary Although the Earth’s inner core has long been thought to be solid, there have not, as yet, been unequivocal observations of inner core shear waves. Here we present observations of the phases pPKJKP and SKJKP for the Flores Sea event of 1996 June 17. The observations support the value of approximately 3.6 km s− 1 for the inner core shear wave velocity and open up new possibilities for exploring the anisotropic structure and the attenuation properties of the inner core. The analysis and validation of the observation is based on a new method that can be used in the search for and identification of inner core shear waves. In this method normal mode synthetics for a solid inner core are compared with those for a fluid inner core. It is only by such comparisons that it is possible to be certain that inner core shear waves, rather than interferences of other phases, are responsible for observed energy maxima in stacked seismic records.

Effects of thermal treatments on the viscoelastic behavior of the interphase relaxation in a compatibilized thermoset/thermoplastic blend

Morphology and viscoelastic properties of a compatibilized epoxy/thermoplastic polymer blend were investigated. Transmission electron microscopy (TEM) showed that the introduction of the compatibilizer significantly reduces the size of the thermoplastic dispersed phase. Dynamic mechanical spectrometry (DMS) revealed an additional loss peak at about 333K at 1Hz in the compatibilized ternary blend spectrum which is detailed as the first unequivocal observation of a `micromechanical transition' in a compatibilized thermoset/thermoplastic blend. In addition, the influence of thermal treatments (which were established according to structural recovery considerations, i.e. accelerated physical aging at Tg−20K and `refreshing' process at Tg+20K) on the viscoelastic behavior (amplitude and temperature position) of the additional loss peak was studied. These investigations revealed that the occurrence of the `micromechanical transition' on DMS spectra depends significantly on the thermal history of the sample and leads to the assumption that the viscoelastic behavior of the interphase relaxation is associated with the conditions of confinement of the components in the interphase zone.

First unequivocal observation of the multiple fully extended conformation (25-helix) in a homopeptide from a Cα-methylated chiral α-amino acid

An X-ray diffraction analysis of pBrBz-[d-(αMe)Leu]3-OtBu revealed that in the crystal state this terminally blocked tripeptide adopts a multiple fully extended conformation (25-helix). This is the first unequivocal observation of such a structure in a homopeptide from a Cα-methylated chiral α-amino acid. No intermolecular NH. . . O=C H- bonds are seen in the crystal packing.

A seven-iron ferredoxin from the thermoacidophilic archaeon Desulfurolobus ambivalens.

A seven-iron ferredoxin was isolated from aerobically grown cells of the hyperthermoacidophilic archaeon Desulfurolobus ambivalens (DSM 3772). The protein is monomeric, with an apparent molecular mass of 15 kDa and contains 7 iron atoms/molecule. The N-terminal sequence shows a large similarity (70% identity) with that of the ferredoxin isolated from the archaeon Sulfolobus acidocaldarius. The EPR characteristics in both the native (oxidized) and dithionite-reduced states of this protein allowed an unequivocal identification of a [3Fe-4S]1+/0 center, with a reduction potential of -270 +/- 20 mV, at pH 7.5. The protein also contains a [4Fe-4S]2+/1+ center with a very low reduction potential (Eo = -540 mV, pH 7.0), which yields a rhombic EPR spectrum upon reduction with sodium dithionite at high pH. The reduction potentials of both centers are slightly pH dependent between pH 6 and 9. The [3Fe-4S] ferredoxin center is able to accept electrons from pyruvate oxidase and NADH oxidase isolated from D. ambivalens. This ferredoxin is present in large amounts (at least 130 mg/kg wet cells), which allowed the unequivocal observation of oxidized [3Fe-4S] clusters in intact D. ambivalens cells.